Water heater



FIG. 1 is a perspective view of a water heater showing my new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a right side elevation view thereof;

FIG. 6 is a greatly enlarged top plan view thereof; and,

FIG. 7 is a greatly enlarged bottom plan view thereof.

The broken lines in the drawings illustrate portions of the water heater and form no part of the claimed design. 

CLAIM The ornamental design for a water heater, as shown and described. 